Waitrose, which is part of the John Lewis partnership, said Delia was leaving so that she could pursue other projects and commitments in 2013.

Television adverts for the supermarket chain over the past few years have featured Smith cooking a variety of her recipes, but more recently, Blumenthal’s creations have proved popular with shoppers.

His Hidden Sauce Figgy Pudding and Christmas Cake were among the festive season’s best-selling products at Waitrose, the company has reported. The Fat Duck chef’s contract with the supermarket is to be renewed from February 2013.

The supermarket has denied there is any ill-feeling between Waitrose and Delia.

Waitrose’s marketing director, Rupert Thomas, said: ‘It has been such a fantastic experience working together and we have been really appreciative of the work Delia has done with Waitrose.

Heston is famed for his experimentation in the kitchen (Picture: Channel 4)

‘We remain on very good terms and will be continuing to work closely with her until the end of February.’

The two TV chefs signed their contracts with Waitrose at the same time, taking on commitments to the supermarket in 2010.

At the time, the supermarket referred to Delia and Heston respectively as ‘Britain’s best loved cook and Britain’s most innovative chef’.

Delia Smith has published over 20 cookbooks and is known for her reliable and often economical cooking.

Heston, on the other hand, has become well-known for his experimental cuisine, with concoctions like snail porridge and vanilla mayonnaise currently featuring on the Fat Duck tasting menu.